This observational study examines the impacts of a statewide hospital payment reform on the hospital care of persons with chronic mental illness by comparing trends in Maryland, which implemented the payment reform, to trends in Pennsylvania, which did not. In 2014, Maryland transitioned from a fee-for-service hospital payment system to a population-based payment system characterized by prospectively assigned global budgets and performance incentives. This change in hospital financing is expected to result in re-organization of hospital care for persons with chronic conditions. For persons with mental illnesses, in particular, it is expected to result in greater integration of thir mental health and general medical care, increased outpatient follow-up following an inpatient stay, and reduced hospital readmissions. However, over a longer time period, incentives created by adverse selection may lead some hospitals to reduce the array of mental health services they offer and their mental health staffing levels. The study's specific aims are to examine how Maryland's payment reform affected: 1) receipt of outpatient follow-up, transitional care management, and/or care integration services after an inpatient stay; 2) inpatient readmission; and 3) and total hospital spending; and 4) to use qualitative methods to explore hospital clinical leaders' perceptions of how Maryland's hospital payment reform affected care integration and access to needed outpatient health care. For Aims 1-3, regression analysis is being used to analyze process of care outcomes for adults (ages 18+) with mental illness who were hospitalized in calendar years 2012 to 2017 in Maryland or Pennsylvania for either a psychiatric condition or a general medical care condition. For Aim 4, we are completing qualitative interviews with directors of hospitals' clinical programs. This study is timely and significant because it will provide some of the first estimates of the impacts of population-based hospital system financing with strict budgetary controls on care coordination and integration for individuals with complex mental health conditions. The proposed study is both timely and innovative because its results will inform policymakers' assessments of how similar reforms are likely to affect the quality and value of hospital care for individuals with chronic mental illness and one or more co-occurring chronic medical problems.